Magnetic resonance study on fractional anisotropy and neuronal metabolite ratios in peritumoral area of cerebral gliomas.

BACKGROUND AND OBJECTIVE

Cerebral gliomas have a tendency to infiltrate the surrounding brain tissue for several centimeters from the core of tumor. The usefulness of structural magnetic resonance (MR) sequences is limited because of their insensitivity for the detection of tumor cells outside the visible tumor border. The aim of this study was to investigate the validity and the repeatability of 2 functional MR methods: fractional anisotropy (FA) and spectroscopy in the assessment of the peritumoral area of cerebral gliomas.

MATERIAL AND METHODS

Forty-five patients with histologically verified brain gliomas underwent diffusion tensor imaging (DTI) and MR spectroscopy (MRS). Metabolic ratios were calculated from choline (Cho), creatine (Cr), N-acetylaspartate (NAA), lactate/lipids (LL), myo-inositol (MI) spectroscopic values obtained within the tumor center, perifocal edema, and distant and contralateral normal-appearing white matter. DTI maps of FA were calculated at the same locations.

RESULTS

A significant gradual increase of FA and a decrease of LL/Cr ratios from the tumor center to the normal-appearing white matter were observed. The Cho/Cr ratio was significantly lower in the distant normal-appearing white matter than in the perifocal edema and the tumor center. The NAA/Cr ratio was significantly reduced in the tumor center, perifocal edema, and distant normal-appearing white matter compared with the contralateral hemisphere. MRS and DTI measurements of glioma and peritumoral area had a high degree of repeatability.

CONCLUSIONS

Our study shows that MRS and DTI measurements are reproducible. The combined use of Cho/Cr, LL/Cr, and FA measurements is a promising MR technique that provides valuable additional information about the location of glioma potential border.